Fluorescence anisotropy of acridinedione dyes in glycerol: Prolate model of ellipsoid

Abstract

Time-dependent reorientations of resorcinol-based acridinidione (ADR) dyes in glycerol were studied using steady-state and time-resolved fluorescence studies. The difference between fluorescence anisotropy decays recorded at 460 nm when exciting at 250 nm and those obtained when exciting at 394 nm are reported. When exciting at 394 nm, the fluorescence anisotropy decay is bi-exponential, while on exciting at 250 nm a mono-exponential fluorescence anisotropy decay is observed. We interpret this in terms of different directions of the absorption dipole at 394 and 250 nm with the emission dipole respectively, which is experimentally validated and further analysed as a prolate model of ellipsoid.

Solvent-Dependent Changes in Molecular Reorientation Dynamics: The Role of Solvent−Solvent Interactions

“…It is the functional form and the time constant(s) associated with the decay of R ( t ) that are related to the local environment of the reorienting molecule. Chuang and Eisenthal developed a model for fluorescence anisotropy decay that provides a means of interpreting anisotropy decay functions containing up to five exponential components. ,,− Despite this potential for complexity, one or two decays are the functional forms observed most commonly. For the excitation and emission transition moments oriented parallel to one another, along the long axis in the chromophore π-system plane, reorientation of the chromophore as a prolate rotor ( D x > D y = D z ) gives rise to a single exponential decay of R ( t ) (eq ), and reorientation as an oblate rotor ( D z > D x = D y ) produces a two-component R ( t ) function, as described by eq .…”

“…The interactions between solvent and solute are thought to depend on solvent molecular structure and organization, and the rotational diffusion dynamics of the solute have been used as a sensitive means of evaluating such interactions. − For many systems, reorientation dynamics can be treated in the context of the modified Debye−Stokes−Einstein (DSE) equation, where solute motion is related to its hydrodynamic volume, the bulk viscosity of the solvent, and the temperature of the system. The initial form of this model is predicated on the assumption of a spherical solute rotating in a continuum solvent, and the predicted form of the anisotropy decay for such a system is a single exponential decay .…”

Photophysical properties of a surfactive long-chain styryl merocyanine dye as fluorescent probe

“…Namely, when the direction of the linear oscillators for the absorption and emission are parallel to each other, r is o0.4; and when those are perpendicular to each other, r is À 0.2; [46]. The positive and the value of anisotropy (r, 0.25-0.31) suggests that the emission dipoles of CMSPB at 485 nm are collinear with the absorption dipole at 385 nm [47]. Furthermore, fluorescence polarization measurements are sensitive to and can provide information about intermolecular interactions over the length scale of the probe molecule [48].…”